Solid-state image pickup apparatus and X-ray inspection system

ABSTRACT

A solid-state image pickup apparatus  1 A includes a photodetecting section  10 A and a signal readout section  20  etc. In the photodetecting section  10 A, M×N pixel units P 1,1  to P M,N  are arrayed in M rows and N columns. When in a first imaging mode, a voltage value according to an amount of charges generated in a photodiode of each of the M×N pixel units in the photodetecting section  10 A is output from the signal readout section  20 . When in a second imaging mode, a voltage value according to an amount of charges generated in the photodiode of each pixel unit included in consecutive M 1  rows in the photodetecting section  10 A is output from the signal readout section  20 . When in the second imaging mode than when in the first imaging mode, the readout pixel pitch in frame data is smaller, the frame rate is higher, and the gain being a ratio of an output voltage value to an input charge amount in the signal readout section  20  is greater.

This is a continuation application of copending application Ser. No. 12/989,129, having a §371 date of Aug. 29, 2011, which is a national stage filing based on PCT International Application No. PCT/JP2009/058006, filed on Apr. 22, 2009. The copending application Ser. No. 12/989,129 is incorporated by reference herein in its entirety.

TECHNICAL FIELD

The present invention relates to a solid-state image pickup apparatus and an X-ray inspection system.

BACKGROUND ART

Solid-state image pickup apparatuses using the CMOS technique are known, and among these, a passive pixel sensor (PPS) type solid-state image pickup apparatus is known. The PPS type solid-state image pickup apparatus includes a photodetecting section where PPS type pixel units including photodiodes for generating charges of amounts according to incident light intensities are two-dimensionally arrayed in M rows and N columns, accumulates, in a capacitor of an integrating circuit, charges generated in the photodiode in response to light incidence in each pixel unit, and outputs a voltage value according to the accumulated charge amount.

Generally, an output terminal of each of the M pixel units of each column is connected with an input terminal of an integrating circuit provided corresponding to the column via a readout wiring provided corresponding to the column. And, in sequence from the first row to the M-th row and row by row, charges generated in the photodiodes of the pixel units are input to a corresponding integrating circuit through a corresponding readout wiring, and a voltage value according to the charge amount is output from the integrating circuit.

The PPS type solid-state image pickup apparatus is used for various purposes, and used, for example, in combination with a scintillator section as an X-ray flat panel also for medical purposes and industrial purposes, and further specifically used also in an X-ray CT apparatus, a microfocus X-ray inspection system, etc. An X-ray inspection system disclosed in Patent Document 1 is a system that images X-rays output from an X-ray generator and transmitted through an inspection object by a solid-state image pickup apparatus to inspect the inspection object, and is capable of imaging X-rays transmitted through the inspection object by the solid-state image pickup apparatus in a plurality of types of imaging modes. These multiple types of imaging modes are mutually different in an imaging region in the photodetecting section.

CITATION LIST Patent Literature

Patent Document 1: Pamphlet of International Publication No. WO2006/109808

SUMMARY OF INVENTION Technical Problem

In Patent Document 1, there is a description to the effect of differentiating the imaging region in the photodetecting section of the solid-state image pickup apparatus depending on the imaging mode, but there is no disclosure of the configuration and operation of the solid-state image pickup apparatus. However, the inventor of the present invention has discovered that a problem exists that the solid-state image pickup apparatus cannot always operate favorably in any of the multiple types of imaging modes depending on the configuration and operation of the solid-state image pickup apparatus.

The present invention has been made in order to solve the above problem, and an object thereof is to provide a solid-state image pickup apparatus and an X-ray inspection system that can operate favorably in each of a plurality of types of imaging modes.

Solution to Problem

A solid-state image pickup apparatus according to the present invention comprises (1) a photodetecting section having M×N pixel units P_(1,1) to P_(M,N) two-dimensionally arranged in M rows and N columns, each of the pixel units including a photodiode and a readout switch connected with the photodiode, the photodiode generating charges corresponding to an intensity of an incident light, (2) a readout wiring L_(O,n) connected with a readout switch of each of the M pixel units P_(1,n) to P_(M,n) of an n-th column in the photodetecting section, for reading out charges generated in the photodiode of any pixel unit of the M pixel units P_(1,n) to P_(M,n) via the readout switch of the pixel unit, (3) a signal readout section connected with each of the readout wirings L_(O,1) to L_(O,N), for holding a voltage value according to an amount of charges input through the readout wiring L_(O,n), and sequentially outputting the held voltage values, and (4) a controlling section that controls an opening and closing operation of the readout switch of each of the M×N pixel units P_(1,1) to P_(M,N) in the photodetecting section and controls an outputting operation of a voltage value in the signal readout section to make a voltage value according to an amount of charges generated in the photodiode of each of the M×N pixel units P_(1,1) to P_(M,N) in the photodetecting section be output from the signal readout section. Further, the controlling section, (a) when in a first imaging mode, makes a voltage value according to an amount of charges generated in the photodiode of each of the M×N pixel units P_(1,1) to P_(M,N) in the photodetecting section be output from the signal readout section, (b) when in a second imaging mode, makes a voltage value according to an amount of charges generated in the photodiode of each pixel unit P_(m,n) included in a specific range of consecutive M₁ rows or N₁ columns in the photodetecting section be output from the signal readout section, and (c) when in the second imaging mode than when in the first imaging mode, makes a readout pixel pitch in frame data based on a voltage value to be output from the signal readout section smaller, makes a frame rate being a number of frames of data to be output per unit time higher, and makes a gain being a ratio of an output voltage value to an input charge amount in the signal readout section greater. However, M and N are each an integer not less than 2, M₁ is an integer less than M, N₁ is an integer less than N, m is an integer not less than 1 and not more than M, and n is an integer not less than 1 and not more than N.

In the solid-state image pickup apparatus according to the present invention, under control by the controlling section, a charge generated in each pixel unit P_(m,n) in response to light incidence into the photodiode is, when a readout switch of the pixel unit is closed, input to the signal readout section through the readout switch and the readout wiring L_(O,n). In the signal readout section, a voltage value according to the input charge amount is output. This solid-state image pickup apparatus has a first imaging mode and a second imaging mode. Under control by the controlling section, when in the first imaging mode, a voltage value according to the amount of charges generated in the photodiode of each of the M×N pixel units P_(1,1) to P_(M,N) in the photodetecting section is output from the signal readout section. On the other hand, when in the second imaging mode, a voltage value according to the amount of charges generated in the photodiode of each pixel unit P_(m,n) included in a specific range of consecutive M₁ rows or N₁ columns in the photodetecting section is output from the signal readout section. Further, when in the second imaging mode than when in the first imaging mode, the readout pixel pitch is made smaller, the frame rate is made higher, and the gain being a ratio of an output voltage value to an input charge amount in the signal readout section is made greater.

In the solid-state image pickup apparatus according to the present invention, the controlling section, when in the second imaging mode, preferably has as the specific range, a range of M₁ rows counted in order from the row closest to the signal readout section out of the M rows in the photodetecting section, and makes a voltage value according to the amount of charges generated in the photodiode of each pixel unit P_(m,n) in the specific range be output from the signal readout section.

The solid-state image pickup apparatus according to the present invention preferably further includes, between the specific range in the photodetecting section and another range excluding the specific range, a disconnection switch provided on each readout wiring L_(O,n), and the controlling section preferably closes the disconnection switch when in the first imaging mode, and opens the disconnection switch when in the second imaging mode.

The solid-state image pickup apparatus according to the present invention preferably includes discharging means that discharges a junction capacitance section of the photodiode in each pixel unit P_(m,n) of another range excluding the specific range in the photodetecting section when in the second imaging mode.

The solid-state image pickup apparatus according to the present invention preferably further includes a scintillator section that is provided so as to cover the M×N pixel units P_(1,1)to P_(M,N) in the photodetecting section.

Moreover, an X-ray inspection system according to the present invention includes the solid-state image pickup apparatus according to the present invention described above and an X-ray generator, and images X-rays output from the X-ray generator and transmitted through an inspection object by the solid-state image pickup apparatus to inspect the inspection object. Moreover, it is preferable that the X-ray generator outputs X-rays at a predetermined divergence angle when in a first output mode, and outputs X-rays at a narrower divergence angle than the predetermined divergence angle when in a second output mode, and that the solid-state image pickup apparatus operates in the first imaging mode when the X-ray generator outputs X-rays in the first output mode, and the solid-state image pickup apparatus operates in the second imaging mode when the X-ray generator outputs X-rays in the second output mode.

Advantageous Effects of Invention

The solid-state image pickup apparatus according to the present invention can operate favorably in each of the multiple types of imaging modes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing a configuration of a solid-state image pickup apparatus 1A according to a first embodiment.

FIG. 2 is a view showing a section of the solid-state image pickup apparatus 1A according to the first embodiment.

FIG. 3 is a circuit diagram of each of the pixel unit P_(m,n) , the integrating circuit S_(n), and the holding circuit H_(n) of the solid-state image pickup apparatus 1A according to the first embodiment.

FIG. 4 is a timing chart for explaining operation of the solid-state image pickup apparatus 1A according to the first embodiment.

FIG. 5 is a timing chart for explaining operation of the solid-state image pickup apparatus 1A according to the first embodiment.

FIG. 6 is a timing chart for explaining operation of the solid-state image pickup apparatus 1A according to the first embodiment.

FIG. 7 is a view showing a configuration of a solid-state image pickup apparatus 1B according to a second embodiment.

FIG. 8 is a configuration diagram of an X-ray inspection system 100 according to the present embodiment.

FIG. 9 is a view showing a modification of the configuration of the solid-state image pickup apparatus 1A, 1B according to the present embodiment.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a best mode for carrying out the present invention will be described in detail with reference to the accompanying drawings. Also, the same components will be denoted with the same reference numerals in the description of the drawings, and overlapping description will be omitted.

First, description will be given of a solid-state image pickup apparatus 1A according to a first embodiment. FIG. 1 is a view showing a configuration of the solid-state image pickup apparatus 1A according to the first embodiment. The solid-state image pickup apparatus 1A shown in this figure includes a photodetecting section 10A, a signal readout section 20, an A/D converting section 30, and a controlling section 40A. Moreover, in the case of use as one for X-ray detection, a scintillator section is provided so as to cover the photodetecting section 10A of the solid-state image pickup apparatus 1A.

For the photodetecting section 10A, M×N pixel units P_(1,1) to P_(M,N) are two-dimensionally arrayed in M rows and N columns. A pixel unit P_(m,n) is located on the m-th row and the n-th column. The pixel units P_(m,n) are arrayed at a pitch of, for example, 100 μm. Here, M and N are each an integer not less than 2, m is an integer not less than 1 and not more than M, and n is an integer not less than 1 and not more than N. The pixel units P_(m,n) are pixel units of the PPS type, and have a common configuration.

In addition, the photodetecting section 10A may have, around the M×N pixel units P_(1,1) to P_(M,N) two-dimensionally arrayed in M rows and N columns, pixel units including photodiodes. However, these surrounding pixel units, which are covered with a shielding portion that prevents incidence of X-rays into the signal readout section 20 and the like and where no light is made incident and no charge is generated, thus do not contribute to imaging. The photodetecting section 10A includes at least the M×N pixel units P_(1,1) to P_(M,N) two-dimensionally arrayed in M rows and N columns as effective pixel units for imaging.

Each of the N pixel units P_(m,1) to P_(m,N) of the m-th row is connected with the controlling section 40A by an m-th row selecting wiring L_(V,m). An output terminal of each of the M pixel units P_(1,n) to P_(M,n) of the n-th column is connected with an integrating circuit S_(n) of the signal readout section 20 by an n-th column readout wiring L_(O,n).

The signal readout section 20 includes N integrating circuits S₁ to S_(N) and the N holding circuits H₁ to H_(N). The integrating circuits S_(n) have a common configuration. Moreover, the holding circuits H_(n) have a common configuration.

Each integrating circuit S_(n) has an input terminal connected with the readout wiring L_(O,n), accumulates charges input to this input terminal, and outputs a voltage value according to the accumulated charge amount from an output terminal to the holding circuit H_(n). Each of the N integrating circuits S₁ to S_(N) is connected with the controlling section 40A by a reset wiring L_(R), and also connected with the controlling section 40A by a gain setting wiring L_(G).

Each holding circuit H_(n) has an input terminal connected with the output terminal of the integrating circuit S_(n), holds a voltage value input to this input terminal, and outputs the held voltage value from an output terminal to a voltage outputting wiring L_(out). Each of the N holding circuits H₁ to H_(N) is connected with the controlling section 40A by a holding wiring L_(H). Moreover, each holding circuit H_(n) is connected with the controlling section 40A by an n-th column selecting wiring L_(H,n).

The A/D converting section 30 is input with a voltage value output to the voltage outputting wiring L_(out) from each of the N holding circuits H₁ to H_(N), and applies A/D converting to the input voltage value (analog value) to output a digital value according to the input voltage value.

The controlling section 40A outputs an m-th row selection control signal Vsel(m) to the m-th row selecting wiring L_(V,m) to supply this m-th row selection control signal Vsel(m) to each of the N pixel units P_(m,1) to P_(m,N) of the m-th row. M row selection control signals Vsel(1) to Vsel(M) sequentially take significant values. The controlling section 40A includes a shift register to sequentially output M row selection control signals Vsel(1) to Vsel(M) as significant values.

The controlling section 40A outputs an n-th column selection control signal Hsel(n) to the n-th column selecting wiring L_(H,n) to supply this n-th column selection control signal Hsel(n) to the holding circuit H_(n). N column selection control signals Hsel(1) to Hsel(N) also sequentially take significant values. The controlling section 40A includes a shift register to sequentially output N column selection control signals Hsel(1) to Hsel(N) as significant values.

Moreover, the controlling section 40A outputs a reset control signal Reset to the reset wiring L_(R) to supply this reset control signal Reset to each of the N integrating circuits S₁ to S_(N). The controlling section 40A outputs a gain setting signal Gain to the gain setting wiring L_(G) to supply this gain setting signal Gain to each of the N integrating circuits S₁ to S_(N). The controlling section 40A outputs a hold control signal Hold to the holding wiring L_(H) to supply this hold control signal Hold to each of the N holding circuits H₁ to H_(N). Further, the controlling section 40A also controls A/D converting in the A/D converting section 30, which is not shown.

The controlling section 40A, as in the above, controls an opening and closing operation of a readout switch SW₁ in each of the M×N pixel units P_(1,1) to P_(M,N) in the photodetecting section 10A, and controls a holding operation and an outputting operation of a voltage value in the signal readout section 20. Accordingly, the controlling section 40A makes a voltage value according to the amount of charges generated in the photodiode of each of the M×N pixel units P_(1,1) to P_(M,N) in the photodetecting section 10A be repeatedly output as frame data from the signal readout section 20.

FIG. 2 is a view showing a section of the solid-state image pickup apparatus 1A according to the first embodiment. For the solid-state image pickup apparatus 1A, a semiconductor substrate 3 is adhered to a flat plate-like base member 2, and a scintillator section 4 is provided on the semiconductor substrate 3. On a main surface of the semiconductor substrate 3, the photodetecting section 10A where the pixel units P_(m,n) are arrayed, the signal readout section 20, the A/D converting section 30 (refer to FIG. 1), and the controlling section 40A (refer to FIG. 1) are formed and integrated, and a bonding pad 50 for signal input/output or power supply is formed. The scintillator section 4 is provided so as to cover the M×N pixel units P_(1,1) to P_(M,N) in the photodetecting section 10A. The scintillator section 4 may be provided by vapor deposition on the semiconductor substrate 3. In addition, each of the signal readout section 20, the A/D converting section 30, and the controlling section 40A may be integrated not on the semiconductor substrate 3 on which the photodetecting section 10A is integrated, but on a semiconductor substrate separate from the semiconductor substrate 3.

FIG. 3 is a circuit diagram of each of the pixel unit P_(m,n), the integrating circuit S_(n), and the holding circuit H_(n) of the solid-state image pickup apparatus 1A according to the first embodiment. Here, a circuit diagram of the pixel unit P_(m,n) as a representative of the M×N pixel units P_(1,1) to P_(M,N) is shown, a circuit diagram of the integrating circuit S_(n) as a representative of the N integrating circuits S₁ to S_(N) is shown, and a circuit diagram of the holding circuit H_(n) as a representative of the N holding circuits H₁ to H_(N) is shown. That is, circuit portions relating to the pixel unit P_(m,n) on the m-th row and the n-th column and the n-th column readout wiring L_(O,n) are shown.

The pixel unit P_(m,n) includes a photodiode PD and a readout switch SW₁. The anode terminal of the photodiode PD is grounded, and the cathode terminal of the photodiode PD is connected with the n-th column readout wiring L_(O,n) via the readout switch SW₁. The photodiode PD generates charge of an amount according to an incident light intensity, and accumulates the generated charge in a junction capacitance section of the photodiode itself. The readout switch SW₁ is supplied with an m-th row selection control signal Vsel(m) passed through the m-th row selecting wiring L_(V,m) from the controlling section 40A. The m-th row selection control signal Vsel(m) is a signal that instructs an opening and closing operation of the readout switch SW₁ in each of the N pixel units P_(m,1) to P_(m,N) of the m-th row in the photodetecting section 10A.

In this pixel unit P_(m,n), when the m-th row selection control signal Vsel(m) is at low level, the readout switch SW₁ opens, and charges generated in the photodiode PD are not output to the n-th column readout wiring L_(O,n) but is accumulated in the junction capacitance section of the photodiode itself. On the other hand, when the m-th row selection control signal Vsel(m) is at high level, the readout switch SW₁ closes, and the charge generated in the photodiode PD and accumulated in the junction capacitance section until then is output to the n-th column readout wiring L_(O,n) through the readout switch SW₁.

The n-th column readout wiring L_(O,n) is connected with the readout switch SW₁ in each of the M pixel units P_(1,n) to P_(M,n) of the n-th column in the photodetecting section 10A. The n-th column readout wiring L_(O,n) reads out charges generated in the photodiode PD of any of the M pixel units P_(1,n) to P_(M,n) via the readout switch SW₁ in this pixel unit, and transfers the charge to the integrating circuit S_(n).

The integrating circuit S_(n) includes an amplifier A₂, an integrating capacitor C₂₁, an integrating capacitor C₂₂, a discharge switch SW₂₁, and a gain setting switch SW₂₂. The integrating capacitor C₂₁ and the discharge switch SW₂₁ are connected in parallel to each other, and provided between an input terminal and an output terminal of the amplifier A₂. Moreover, the integrating capacitor C₂₂ and the gain setting switch SW₂₂ are connected in series to each other, and provided between an input terminal and an output terminal of the amplifier A₂, so that the gain setting switch SW₂₂ is connected to the input terminal side of the amplifier A₂. The input terminal of the amplifier A₂ is connected with the n-th column readout wiring L_(O,n).

The discharge switch SW₂₁ is supplied with a reset control signal Reset through the reset wiring L_(R) from the controlling section 40A (refer to FIG. 1). The reset control signal Reset is a signal that instructs an opening and closing operation of the discharge switch SW₂₁ in each of the N integrating circuits S₁ to S_(N). The gain setting switch SW₂₂ is supplied with a gain setting signal Gain through the gain setting wiring L_(G) from the controlling section 40A. The gain setting signal Gain is a signal that instructs an opening and closing operation of the gain setting switch SW₂₂ in each of the N integrating circuits S₁ to S_(N).

In this integrating circuit S_(n), the integrating capacitors C₂₁, C₂₂ and the gain setting switch SW₂₂ compose a feedback capacitance section where the capacitance value is variable. That is, when the gain setting signal Gain is at low level and the gain setting switch SW₂₂ is open, the capacitance value of the feedback capacitance section is equal to a capacitance value of the integrating capacitor C₂₁. On the other hand, when the gain setting signal Gain is at high level and the gain setting switch SW₂₂ is closed, the capacitance value of the feedback capacitance section is equal to a sum of respective capacitance values of the integrating capacitors C₂₁, C₂₂. When the reset control signal Reset is at high level, the discharge switch SW₂₁ closes, the feedback capacitance section is discharged, and a voltage value to be output from the integrating circuit S_(n) is initialized. On the other hand, when the reset control signal Reset is at low level, the discharge switch SW₂₁ opens, a charge input to the input terminal is accumulated in the feedback capacitance section, and a voltage value according to the accumulated charge amount is output from the integrating circuit S_(n).

The holding circuit H_(n) includes an input switch SW₃₁, an output switch SW₃₂, and a holding capacitor C₃. One end of the holding capacitor C₃ is grounded. The other end of the holding capacitor C₃ is connected with the output terminal of the integrating circuit S_(n) via the input switch SW₃₁, and connected with the voltage outputting wiring L_(out) via the output switch SW₃₂. The input switch SW₃₁ is supplied with a hold control signal Hold passed through the holding wiring L_(H) from the controlling section 40A. The hold control signal Hold is a signal that instructs an opening and closing operation of the input switch SW₃₁ in each of the N holding circuits H₁ to H_(N). The output switch SW₃₂ is supplied with an n-th column selection control signal Hsel(n) passed through the n-th column selecting wiring L_(H,n) from the controlling section 40A. The n-th column selection control signal Hsel(n) is a signal that instructs an opening and closing operation of the output switch SW₃₂ of the holding circuit H_(n).

In this holding circuit H_(n), when the hold control signal Hold switches from high level to low level, the input switch SW₃₁ switches from a closed state to an open state, and a voltage value being input to the input terminal at this time is held in the holding capacitor C₃. Moreover, when the n-th column selection control signal Hsel(n) is at high level, the output switch SW₃₂ closes, and the voltage value held in the holding capacitor C₃ is output to the voltage outputting wiring L_(out).

The controlling section 40A shown in FIG. 1, when outputting a voltage value according to a received light intensity in each of the N pixel units P_(m,1) to P_(m,N) of the m-th row in the photodetecting section 10A, instructs temporary closing and then opening of the discharge switch SW₂₁ in each of the N integrating circuits S₁ to S_(N) by a reset control signal Reset, and then instructs closing of the readout switch SW₁ in each of the N pixel units P_(m,1) to P_(m,N) of the m-th row in the photodetecting section 100A for a predetermined period by an m-th row selection control signal Vsel(m). The controlling section 40A, in this predetermined period, instructs switching of the input switch SW₃₁ in each of the N holding circuits H₁ to H_(N) from a closed state to an open state by a hold control signal Hold. Then, the controlling section 40A, after the predetermined period, instructs sequential closing of the output switches SW₃₂ in the respective N holding circuits H₁ to H_(N) for a predetermined period by column selection control signals Hsel(1) to Hsel(N). The controlling section 40A performs such control as in the above for the respective rows in sequence.

The solid-state image pickup apparatus 1A according to the present embodiment particularly has a first imaging mode and a second imaging mode. The first imaging mode and the second imaging mode are mutually different in an imaging region in the photodetecting section 10A. The controlling section 40A, when in the first imaging mode, makes a voltage value according to the amount of charges generated in the photodiode PD of each of the M×N pixel units P_(1,1) to P_(M,N) in the photodetecting section 10A be output from the signal readout section 20. Also, the controlling section 40A, when in the second imaging mode, makes a voltage value according to the amount of charges generated in the photodiode PD of each pixel unit P_(m,n) included in a specific range of consecutive M₁ rows or N₁ columns in the photodetecting section 10A be output from the signal readout section 20. In addition, M₁ is an integer less than M, and N₁ is an integer less than N.

The controlling section 40A, when in the second imaging mode, preferably has a range of consecutive M₁ rows in the photodetecting section 10A as the specific range, and more preferably has, as the specific range, a range of M₁ rows counted in order from the row closest to the signal readout section 20 out of the M rows in the photodetecting section 10A. That is, where the row closest to the signal readout section 20 in the photodetecting section 10A is the first row as shown in FIG. 1, the controlling section 40A, when in the second imaging mode, preferably has a range from the first row to the M₁-th row in the photodetecting section 10A as the specific range, and makes a voltage value according to the amount of charges generated in the photodiode PD of each pixel unit P_(m,n) of this specific range (first row to M₁-th row) be output from the signal readout section 20. This makes it highly likely, even with the n-th column readout wiring L_(O,n) disconnected, to allow making a voltage value according to the amount of charges generated in the photodiode PD of each pixel unit P_(m,n) of the specific range be normally output from the signal readout section 20 when in the second imaging mode.

Moreover, the controlling section 40A, when in the second imaging mode than when in the first imaging mode, makes the readout pixel pitch in the frame data based on the voltage value to be output from the signal readout section 20 smaller, and the frame rate being the number of frames of data to be output per unit time higher, and the gain being a ratio of an output voltage value to an input charge amount in the signal readout section 20 greater.

For example, assuming that the solid-state image pickup apparatus 1A according to the present embodiment is used in the X-ray inspection system disclosed in Patent Document 1, and this X-ray inspection system is used for a dental application, the following applies. At this time, the first imaging mode corresponds to a CT mode described in Patent Document 1, and the second imaging mode corresponds to a panoramic mode or cephalographic mode described in Patent Document 1. When in the first imaging mode, the pixel pitch is 200 μm, and the frame rate (the number of frames (F) per 1 second (s)) is 30 F/s. On the other hand, when in the second imaging mode, the pixel pitch is 100 μm, and the frame rate is 300 F/s.

Thus, when in the second imaging mode than when in the first imaging mode, the pixel pitch is smaller, and the frame rate is higher. Therefore, when in the first imaging mode, it is necessary to perform binning readout in order to make the pixel pitch larger than when in the second imaging mode. Moreover, when in the second imaging mode than when in the first imaging mode, the amount of light that each pixel of each frame of data receives is smaller.

Then, the controlling section 40A differentiates the gain being a ratio of an output voltage value to an input charge amount in the signal readout section 20 between the first imaging mode and second imaging mode. That is, when each integrating circuit S_(n) is configured as shown in FIG. 3, the controlling section 40A, by controlling to open and close the gain setting switch SW₂₂ by the gain setting signal Gain, appropriately sets the capacitance value of the feedback capacitance section of each integrating circuit S_(n) to differentiate the gain between the first imaging mode and second imaging mode.

More specifically, when in the first imaging mode, the controlling section 40A closes the gain setting switch SW₂₂ to thereby make the capacitance value of the feedback capacitance section equal to a sum of the respective capacitance values of the integrating capacitor C₂₁ and integrating capacitor C₂₂. On the other hand, when in the second imaging mode, the controlling section 40A opens the gain setting switch SW₂₂ to thereby make the capacitance value of the feedback capacitance section equal to the capacitance value of the integrating capacitor C₂₁. In this way, when in the second imaging mode than when in the first imaging mode, the capacitance value of the feedback capacitance section of each integrating circuit S_(n) can be made smaller to make the gain larger. This allows, between the first imaging mode and second imaging mode, the respective pixel data to have mutually close values, and allows operating favorably in each imaging mode.

Next, operation of the solid-state image pickup apparatus 1A according to the first embodiment will be described. In the solid-state image pickup apparatus 1A according to the present embodiment, as a result of level changes of each of the M row selection control signals Vsel(1) to Vsel(M), the N column selection control signals Hsel(1) to Hsel(N), the reset control signal Reset, and the hold control signal Hold at predetermined timings under control by the controlling section 40A, light made incident on the photodetecting section 10A can be imaged to obtain frame data.

The operation of the solid-state image pickup apparatus 1A when in the first imaging mode is as follows. FIG. 4 is a timing chart for explaining operation of the solid-state image pickup apparatus 1A according to the first embodiment. Here, description will be given of the operation when in the first imaging mode for binning readout of 2 rows and 2 columns. That is, the readout pixel pitch in the frame data is set to two times the pitch of the pixel units. In each integrating circuit S_(n), the gain setting switch SW₂₂ is closed, the capacitance value of the feedback capacitance section is set to a large value, and the gain is set to a small value.

This figure shows, in order from the top, (a) the reset control signal Reset for instructing an opening and closing operation of the discharge switch SW₂₁ in each of the N integrating circuits S₁ to S_(N), (b) the first row selection control signal Vsel(1) and the second row selection control signal Vsel(2) for instructing an opening and closing operation of the readout switch SW₁ in each of the pixel units P_(1,1) to P_(1,N) and P_(2,1) to P_(2,N) of the first and the second rows in the photodetecting section 100A, (c) the third row selection control signal Vsel(3) and the fourth row selection control signal Vsel(4) for instructing an opening and closing operation of the readout switch SW₁ in each of the pixel units P_(3,1) to P_(3,N) and P_(4,1) to P_(4,N) of the third and the fourth rows in the photodetecting section 10A, and (d) the hold control signal Hold for instructing an opening and closing operation of the input switch SW₃₁ in each of the N holding circuits H₁ to H_(N).

Moreover, this figure further goes on to show, in order, (e) the first column selection control signal Hsel(1) for instructing an opening and closing operation of the output switch SW₃₂ of the holding circuit H₁, (f) the second column selection control signal Hsel(2) for instructing an opening and closing operation of the output switch SW₃₂ of the holding circuit H₂, (g) the third column selection control signal Hsel(3) for instructing an opening and closing operation of the output switch SW₃₂ of the holding circuit H₃, (h) the n-th column selection control signal Hsel(n) for instructing an opening and closing operation of the output switch SW₃₂ of the holding circuit H_(n), and (i) the N-th column selection control signal Hsel(N) for instructing an opening and closing operation of the output switch SW₃₂ of the holding circuit H_(N).

Charges generated in the photodiode PD of each of the 2N pixel units P_(1,1) to P_(1,N) and P_(2,1) to P_(2,N) of the first and the second rows and accumulated in the junction capacitance section is read out as follows. Before the time t₁₀, each of the M row selection control signals Vsel(1) to Vsel(M), the N column selection control signals Hsel(1) to Hsel(N), the reset control signal Reset, and the hold control signal Hold is at low level.

During a period from the time t₁₀ to the time t₁₁, the reset control signal Reset to be output from the controlling section 40A to the reset wiring L_(R) becomes high level, and accordingly, in each of the N integrating circuits S₁ to S_(N), the discharge switch SW₂₁ closes, and the integrating capacitors C₂₁, C₂₂ are discharged. Moreover, during a period from the time t₁₂ to the time t₁₅ after the time t₁₁, the first row selection control signal Vsel(1) to be output from the controlling section 40A to the first row selecting wiring L_(V,1) becomes high level, and accordingly, the readout switch SW₁ in each of the N pixel units P_(1,1) to P_(1,N) of the first row in the photodetecting section 10A closes. Moreover, during the same period (t₁₂ to t₁₅), the second row selection control signal Vsel(2) to be output from the controlling section 40A to the second row selecting wiring L_(V,2) becomes high level, and accordingly, the readout switch SW₁ in each of the N pixel units P_(2,1) to P_(2,N) of the second row in the photodetecting section 10A closes.

In the period (t₁₂ to t₁₅), during a period from the time t₁₃ to the time t₁₄, the hold control signal Hold to be output from the controlling section 40A to the holding wiring L_(H) becomes high level, and accordingly, the input switch SW₃₁ closes in each of the N holding circuits H₁ to H_(N).

In this period (t₁₂ to t₁₅), the readout switch SW₁ in each pixel unit P_(1,n), P_(2,n) of the first and the second rows is closed, and the discharge switch SW₂₁ of each integrating circuit S_(n) is open. Therefore, charges generated in the photodiode PD of the pixel unit P_(1,n) and accumulated in the junction capacitance section until then are transferred to and accumulated in the integrating capacitors C₂₁, C₂₂ of the integrating circuit S_(n) through the readout switch SW₁ of the pixel unit P_(1,n) and the n-th column readout wiring L_(O,n). Moreover, simultaneously, charges generated in the photodiode PD of the pixel unit P_(2,n) and accumulated in the junction capacitance section until then are also transferred to and accumulated in the integrating capacitors C₂₁, C₂₂ of the integrating circuit S_(n) through the readout switch SW₁ of the pixel unit P_(2,n) and the n-th column readout wiring L_(O,n). Then, a voltage value according to the amount of charges accumulated in the integrating capacitors C₂₁, C₂₂ of each integrating circuit S_(n) is output from the output terminal of the integrating circuit S_(n).

At the time t₁₄ in the period (t₁₂ to t₁₅), as a result of the hold control signal Hold switching from high level to low level, in each of the N holding circuits H₁ to H_(N), the input switch SW₃₁ switches from a closed state to an open state, and a voltage value being output from the output terminal of the integrating circuit S_(n) and being input to the input terminal of the holding circuit H_(n) at this time is held in the holding capacitor C₃.

Then, after the period (t₁₂ to t₁₅), column selection control signals Hsel(1) to Hsel(N) to be output from the controlling section 40A to the column selecting wirings L_(H,1) to L_(H,N) sequentially become high level for a predetermined period, and accordingly, the output switches SW₃₂ in the N holding circuits H₁ to H_(N) sequentially close for the predetermined period, the voltage values held in the holding capacitors C₃ of the holding circuits H, are sequentially output to the voltage outputting wiring L_(out) through the output switches SW₃₂. The voltage value V_(out) to be output to the voltage outputting wiring L_(out) indicates a value of the received light intensities in the respective photodiodes PD of the 2N pixel units P_(1,1) to P_(1,N) and P_(2,1) to P_(2,N) of the first and the second rows being added in the column direction.

The voltage values sequentially output from the respective N holding circuits H₁ to H_(N) are input to the A/D converting section 30, and converted to digital values according to the input voltage values. Then, of the N digital values output from the A/D converting section 30, digital values corresponding to each of the first and the second columns are added, digital values corresponding to each of the third and the fourth columns are added, and the following digital values are continuously added two by two.

Subsequently, charges generated in the photodiode PD of each of the 2N pixel units P_(3,1) to P_(3,N) and P_(4,1) to P_(4,N) of the third and the fourth rows and accumulated in the junction capacitance section are read out as follows.

During a period from the time t₂₀ to the time t₂₁, the reset control signal Reset to be output from the controlling section 40A to the reset wiring L_(R) becomes high level, and accordingly, in each of the N integrating circuits S₁ to S_(N), the discharge switch SW₂₁ closes, and the integrating capacitors C₂₁, C₂₂ are discharged. Moreover, during a period from the time t₂₂ to the time t₂₅ after the time t₂₁, the third row selection control signal Vsel(3) to be output from the controlling section 40A to the third row selecting wiring L_(V,3) becomes high level, and accordingly, the readout switch SW₁ in each of the N pixel units P₃₁₁ to P_(3,N) of the third row in the photodetecting section 10A closes. Moreover, during the same period (t₁₂ to t₁₅), the fourth row selection control signal Vsel(4) to be output from the controlling section 40A to the fourth row selecting wiring L_(V,4) becomes high level, and accordingly, the readout switch SW₁ in each of the N pixel units P_(4,1) to P_(4,N) of the fourth row in the photodetecting section 10A closes.

In this period (t₂₂ to t₂₅), during a period from the time t₂₃ to the time t₂₄, the hold control signal Hold to be output from the controlling section 40A to the holding wiring L_(H) becomes high level, and accordingly, the input switch SW₃₁ closes in each of the N holding circuits H₁ to H_(N).

Then, after the period (t₂₂ to t₂₅), column selection control signals Hsel(1) to Hsel(N) to be output from the controlling section 40A to the column selecting wirings L_(H,1) to L_(H,N) sequentially become high level for a predetermined period, and accordingly, the output switches SW₃₂ in the respective N holding circuits H₁ to H_(N) sequentially close for the predetermined period. Thus, a voltage value V_(out) indicating a value of the received light intensities in the respective photodiodes PD of the 2N pixel units P_(3,1) to P_(3,N) and P_(4,1) to P_(4,N) of the third and the fourth rows being added in the column direction is output to the voltage outputting wiring L_(out).

The voltage values sequentially output from the respective N holding circuits H₁ to H_(N) are input to the A/D converting section 30, and converted to digital values according to the input voltage values. Then, of the N digital values output from the A/D converting section 30, digital values corresponding to each of the first and the second columns are added, digital values corresponding to each of the third and the fourth columns are added, and the following digital values are continuously added two by two.

When in the first imaging mode, subsequent to the operation for the first and the second rows as in the above, and the subsequent operation for the third and the fourth rows, the same operation is performed for the fifth to the M-th rows, so that frame data indicating an image captured in one time of imaging is obtained. When the operation is completed for the M-th row, the same operation is again performed in a range from the first row to the M-th row, and frame data indicating a next image is obtained. By thus repeating the same operation with a predetermined period, voltage values V_(out) indicating a two-dimensional intensity distribution of an image of light received by the photodetecting section 10A are output to the voltage outputting wiring L_(out), and the frame data is repeatedly obtained. Moreover, the readout pixel pitch in the frame data to be obtained at this time is two times the pitch of the pixel units.

On the other hand, the operation of the solid-state image pickup apparatus 1A when in the second imaging mode is as follows. FIG. 5 and FIG. 6 are timing charts for explaining operation of the solid-state image pickup apparatus 1A according to the first embodiment. No binning readout is performed in the second imaging mode. That is, the readout pixel pitch in the frame data is made equal to the pitch of the pixel units. In each integrating circuit S_(n), the gain setting switch SW₂₂ is open, the capacitance value of the feedback capacitance section is set to a small value, and the gain is set to a large value.

FIG. 5 shows the operation for each of the first and the second rows in the photodetecting section 10A. This figure shows, in order from the top, (a) the reset control signal Reset, (b) the first row selection control signal Vsel(1), (c) the second row selection control signal Vsel(2), (d) the hold control signal Hold, (e) the first column selection control signal Hsel(1), (f) the second column selection control signal Hsel(2), (g) the third column selection control signal Hsel(3), (h) the n-th column selection control signal Hsel(n), and (i) the N-th column selection control signal Hsel(N).

Charges generated in the photodiode PD of each of the N pixel units P_(1,1) to P_(1,N) of the first row and accumulated in the junction capacitance section is read out as follows. Before the time t₁₀, each of the M row selection control signals Vsel(1) to Vsel(M), the N column selection control signals Hsel(1) to Hsel(N), the reset control signal Reset, and the hold control signal Hold are at low level.

During a period from the time t₁₀ to the time t₁₁, the reset control signal Reset to be output from the controlling section 40A to the reset wiring L_(R) becomes high level, and accordingly, in each of the N integrating circuits S₁ to S_(N), the discharge switch SW₂₁ closes, and the integrating capacitor C₂₁ is discharged. Moreover, during a period from the time t₁₂ to the time t₁₅ after the time t₁₁, the first row selection control signal Vsel(1) to be output from the controlling section 40A to the first row selecting wiring L_(V,1) becomes high level, and accordingly, the readout switch SW₁ in each of the N pixel units P_(1,1) to P_(1,N) of the first row in the photodetecting section 10A closes.

In this period (t₁₂ to t₁₅), during a period from the time t₁₃ to the time t₁₄, the hold control signal Hold to be output from the controlling section 40A to the holding wiring L_(H) becomes high level, and accordingly, the input switch SW₃₁ closes in each of the N holding circuits H₁ to H_(N).

In the period (t₁₂ to t₁₅), the readout switch SW₁ in each pixel unit P_(1,n) of the first row is closed, and the discharge switch SW₂₁ of each integrating circuit S_(n) is open, and therefore, charges generated in the photodiode PD of each pixel unit P_(1,n) and accumulated in the junction capacitance section until then are transferred to and accumulated in the integrating capacitor C₂₁ of the integrating circuit S_(n) through the readout switch SW₁ of the pixel unit P_(1,n) and the n-th column readout wiring L_(O,n). Then, a voltage value according to the amount of charges accumulated in the integrating capacitor C₂₁ of each integrating circuit S_(n) is output from the output terminal of the integrating circuit S_(n).

At the time t₁₄ in the period (t₁₂ to t₁₅), as a result of the hold control signal Hold switching from high level to low level, in each of the N holding circuits H₁ to H_(N), the input switch SW₃₁ switches from a closed state to an open state, and a voltage value being output from the output terminal of the integrating circuit S_(n) and being input to the input terminal of the holding circuit H_(n) at this time is held in the holding capacitor C₃.

Then, after the period (t₁₂ to t₁₅), column selection control signals Hsel(1) to Hsel(N) to be output from the controlling section 40A to the column selecting wirings L_(H,1) to L_(H,N) sequentially become high level for a predetermined period, and accordingly, the output switches SW₃₂ in the respective N holding circuits H₁ to H_(N) sequentially close for the predetermined period, and the voltage values held in the holding capacitors C₃ of the holding circuits H_(n) are sequentially output to the voltage outputting wiring L_(out) through the output switches SW₃₂. The voltage value V_(out) to be output to the voltage outputting wiring L_(out) indicates the received light intensity in the photodiode PD of each of the N pixel units P_(1,1) to P_(1,N) of the first row.

Subsequently, a charge generated in the photodiode PD of each of the N pixel units P_(2,1) to P_(2,N) of the second row and accumulated in the junction capacitance section is read out as follows.

During a period from the time t₂₀ to the time t₂₁, the reset control signal Reset to be output from the controlling section 40A to the reset wiring L_(R) becomes high level, and accordingly, in each of the N integrating circuits S₁ to S_(N), the discharge switch SW₂₁ closes, and the integrating capacitor C₂₁ is discharged. Moreover, during a period from the time t₂₂ to the time t₂₅ after the time t₂₁, the second row selection control signal Vsel(2) to be output from the controlling section 40A to the second row selecting wiring L_(V,2) becomes high level, and accordingly, the readout switch SW₁ in each of the N pixel units P_(2,1) to P_(2,N) of the second row in the photodetecting section 10A closes.

In this period (t₂₂ to t₂₅), during a period from the time t₂₃ to the time t₂₄, the hold control signal Hold to be output from the controlling section 40A to the holding wiring L_(H) becomes high level, and accordingly, the input switch SW₃₁ closes in each of the N holding circuits H₁ to H_(N).

Then, after the period (t₂₂ to t₂₅), column selection control signals Hsel(1) to Hsel(N) to be output from the controlling section 40A to the column selecting wirings L_(H,1) to L_(H,N) sequentially become high level for a predetermined period, and accordingly, the output switches SW₃₂ in the respective N holding circuits H₁ to H_(N) sequentially close for the predetermined period. Thus, a voltage value V_(out) indicating the received light intensity in the photodiode PD of each of the N pixel units P_(2,1) to P_(2,N) of the second row is output to the voltage outputting wiring L_(out).

When in the second imaging mode, subsequent to the operation for the first and the second rows as in the above, the same operation is performed for the third to the M₁-th rows, so that frame data indicating an image captured in one time of imaging is obtained. When the operation is completed for the M₁-th row, the same operation is again performed in a range from the first row to the M₁-th row, and frame data indicating a next image is obtained. By thus repeating the same operation with a predetermined period, voltage values V_(out) indicating a two-dimensional intensity distribution of an image of light received by the photodetecting section 10A are output to the voltage outputting wiring L_(out), and the frame data is repeatedly obtained.

When in the second imaging mode, output of a voltage value from the signal readout section 20 to the voltage outputting wiring L_(out) is not performed in terms of a range from the (M₁+1)-th row to the M-th row. However, also in each pixel unit P_(m,n) of the range from the (M₁+1)-th row to the M-th row, charges generated in response to light incidence into the photodiode PD are accumulated in the junction capacitance section of the photodiode PD, and exceed a saturation level of the junction capacitance section over time. If the amount of charges accumulated in the junction capacitance section of the photodiode PD exceeds the saturation level, a surplus of charges over the saturation level overflows to neighboring pixel units. If the neighboring pixel units belong to the M₁-th row, voltage values to be output from the signal readout section 20 to the voltage outputting wiring L_(out) in terms of the neighboring pixel units are incorrect.

Therefore, it is favorable to provide discharging means for discharging the junction capacitance section of the photodiode PD in each pixel unit P_(m,n) of the range from the (M₁+1)-th row to the M-th row when in the second imaging mode. The solid-state image pickup apparatus 1A according to the present embodiment performs, as such discharging means, the operation as shown in FIG. 6 when in the second imaging mode to transfer to the integrating circuit S_(n) the charges accumulated in the junction capacitance section of the photodiode PD in each pixel unit P_(m,n) of the range from the (M₁+1)-th row to the M-th row, thereby discharging the junction capacitance section of the photodiode PD.

FIG. 6 shows the operation for each of the M₁-th and the (M₁+1)-th rows in the photodetecting section 10A. This figure shows, in order from the top, (a) the reset control signal Reset, (b) the M₁-th row selection control signal Vsel(M₁), (c) the (M₁+1)-th row selection control signal Vsel(M₁+1), (d) the hold control signal Hold, (e) the first column selection control signal Hsel(1), (f) the second column selection control signal Hsel(2), (g) the third column selection control signal Hsel(3), (h) the n-th column selection control signal Hsel(n), and (i) the N-th column selection control signal Hsel(N).

The operation for the M₁-th row in the period from the time t₄₀ to the time t₃₀ shown in FIG. 6 is the same as the operation for the first row in the period from the time t₁₀ to the time t₂₀ shown in FIG. 5. However, during a period from the time t₄₂ to the time t₄₅, the M₁-th row selection control signal Vsel(M₁) to be output from the controlling section 40A to the M₁-th row selecting wiring L_(V,M1) becomes high level, and accordingly, the readout switch SW₁ in each of the N pixel units P_(M1,1) to P_(M1,N) of the M₁-th row in the photodetecting section 10A closes.

When the operation for the M₁-th row is completed when in the second imaging mode, from the time t₅₀ onward, the operation for the range from the (M₁+1)-th row to the M-th row is performed. That is, from the time t₅₀ onward, the reset control signal Reset to be output from the controlling section 40A to the reset wiring L_(R) becomes high level, and accordingly, in each of the N integrating circuits S₁ to S_(N), the discharge switch SW₂₁ closes. Moreover, during a period from the time t₅₀ onward where the discharge switch SW₂₁ is closed, the (M₁+1)-th row to the M-th row selection control signals Vsel(M₁+1) to Vsel(M) become high level, and accordingly, the readout switch SW₁ in each pixel unit P_(m,n) of the range from the (M₁+1)-th row to the M-th row in the photodetecting section 10A closes.

Thus, as a result of the readout switch SW₁ in each pixel unit P_(m,n) of the range from the (M₁+1)-th row to the M-th row closing when in the second imaging mode, the charges accumulated in the junction capacitance section of the photodiode PD in the pixel unit are transferred to the integrating circuit S_(n), and as a result of the discharge switch SW₂₁ closing in each integrating circuit S_(n), the integrating capacitor C₂₁ of each integrating circuit S_(n) is always in a discharged state. In this way, the junction capacitance section of the photodiode PD in each pixel unit P_(m,n) of the range from the (M₁+1)-th row to the M-th row can be discharged when in the second imaging mode.

At this time, in terms of the range from the (M₁+1)-th row to the M-th row, the row selection control signals Vsel(M₁+1) to Vsel(M) may sequentially become high level, but a plurality of row selection control signals of the row selection control signals Vsel(M₁+1) to Vsel(M) may simultaneously become high level, and all of the row selection control signals Vsel(M₁+1) to Vsel(M) may simultaneously become high level. Thus, in terms of the range from the (M₁+1)-th row to the M-th row, as a result of a plurality or all of the row selection control signals simultaneously becoming high level, the junction capacitance section of the photodiode PD in each pixel unit P_(m,n) can be discharged in a shorter time.

Meanwhile, as another imaging mode for outputting data of a smaller number of pixel units than in the first imaging mode from the signal readout section 20, a voltage value according to the amount of charges generated in the photodiode PD of each pixel unit P_(m,n) included in consecutive N₁ columns in the photodetecting section 10A may be output from the signal readout section 20. Here, N₁ is an integer less than N. However, in the imaging mode for thus outputting data of each pixel unit P_(m,n) of the N₁ columns from the signal readout section 20, it is necessary to output the M row selection control signals Vsel(1) to Vsel(M) from the controlling section 40A in order to obtain one frame of data. In contrast thereto, the solid-state image pickup apparatus 1A according to the present embodiment, for which, it suffices, when in the second imaging mode for outputting data of each pixel unit P_(m,n) of the M₁ rows from the signal readout section 20, to output M₁ row selection control signals Vsel(1) to Vsel(M₁) from the controlling section 40A in order to obtain one frame of data, can thus perform a high-speed operation.

In addition, in the timing charts shown in FIG. 4 to FIG. 6 described thus far, each integrating circuit S_(n) is initialized after readout of a voltage value from each holding circuit H_(n) is completed. However, if after an output voltage value of each integrating circuit S_(n) is held by the holding circuit H_(n), the reset control signal Reset may be made high level to initialize each integrating circuit S_(n) during a period of reading out a voltage value from each holding circuit H_(n). This allows a higher-speed operation.

Next, description will be given of a solid-state image pickup apparatus 1B according to a second embodiment. FIG. 7 is a view showing a configuration of the solid-state image pickup apparatus 1B according to the second embodiment. The solid-state image pickup apparatus 1B shown in this figure includes a photodetecting section 10B, a signal readout section 20, an A/D converting section 30, and a controlling section 40B. Moreover, in the case of use as one for X-ray detection, a scintillator section is provided so as to cover the photodetecting section 10B of the solid-state image pickup apparatus 1B.

As compared with the configuration of the solid-state image pickup apparatus 1A according to the first embodiment shown in FIG. 1, the solid-state image pickup apparatus 1B according to the second embodiment shown in FIG. 7 is different in that a disconnection switch SW1 _(n) and a discharge switch SW2 _(n) are provided on each n-th column readout wiring L_(O,n), and is different in including a controlling section 40B in place of the controlling section 40A.

Each disconnection switch SW1 _(n) is provided, on the readout wiring L_(O,n), between the M₁-th row and the (M₁+1)-th row in the photodetecting section 10B. That is, when the disconnection switch SW1 _(n) is closed, each pixel unit P_(m,n) in a range from the first row to the M-th row is connected via the readout wiring L_(O,n) with the signal readout section 20. On the other hand, when the disconnection switch SW1 _(n) is open, each pixel unit P_(m,n) in a range from the first row to the M₁-th row is connected via the readout wiring L_(O,n) with the signal readout section 20, but each pixel unit P_(m,n) in a range from the (M₁+1)-th row to the M-th row is disconnected from the signal readout section 20. Each disconnection switch SW1 _(n) is connected via a disconnection wiring L_(D1) with the controlling section 40B, and supplied with a disconnection control signal Disconnect passed through the disconnection wiring L_(D1) from the controlling section 40B. The disconnection control signal Disconnect is a signal for instructing an opening and closing operation of each disconnection switch SW1 _(n).

Each discharge switch SW2 _(n) is provided, on the readout wiring L_(O,n), at a side further distant from the signal readout section 20 than the position where the disconnection switch SW1 _(n) is provided. One end of the discharge switch SW2 _(n) is connected, via the readout wiring L_(O,n), with each pixel unit P_(m,n) in the range from the (M₁+1)-th row to the M-th row. The other end of the discharge switch SW2 _(n) is grounded. Each discharge switch SW2 _(n) is connected via a discharge wiring L_(D2) with the controlling section 40B, and supplied with a discharge control signal Discharge passed through the discharge wiring L_(D2) from the controlling section 40B. The discharge control signal Discharge is a signal for instructing an opening and closing operation of each discharge switch SW2 _(n).

The controlling section 40B, in the same manner as the controlling section 40A in the first embodiment, outputs an m-th row selection control signal Vsel(m) to the m-th row selecting wiring L_(V,m), outputs an n-th column selection control signal Hsel(n) to the n-th column selecting wiring L_(H,n), outputs a discharge control signal Reset to the discharge wiring L_(R), outputs a gain setting signal Gain to the gain setting wiring L_(G), and outputs a hold control signal Hold to the holding wiring L_(H).

In addition, the controlling section 40B outputs a disconnection control signal Disconnect to the disconnection wiring L_(D1) to supply this disconnection control signal Disconnect to each of the N disconnection switches SW1 ₁ to SW1 _(N). Moreover, the controlling section 40B outputs a discharge control signal Discharge to the discharge wiring L_(D2) to supply this discharge control signal Discharge to each of the N discharge switches SW2 ₁ to SW2 _(N).

The solid-state image pickup apparatus 1B according to the second embodiment also has a first imaging mode and a second imaging mode. The first imaging mode and the second imaging mode are mutually different in an imaging region in the photodetecting section 10B. The controlling section 40B, when in the first imaging mode, makes a voltage value according to the amount of charges generated in the photodiode PD of each of the M×N pixel units P_(1,1) to P_(M,N) in the photodetecting section 10B be output from the signal readout section 20. Also, the controlling section 40B, when in the second imaging mode, makes a voltage value according to the amount of charges generated in the photodiode PD of each pixel unit P_(m,n) of the range from the first row to the M₁-th row in the photodetecting section 10B be output from the signal readout section 20.

Moreover, the controlling section 40B, when in the second imaging mode than when in the first imaging mode, makes the readout pixel pitch in the frame data based on the voltage value to be output from the signal readout section 20 smaller, and the frame rate being the number of frames of data to be output per unit time higher, and the gain being a ratio of an output voltage value to an input charge amount in the signal readout section 20 greater.

In the solid-state image pickup apparatus 1B according to the second embodiment, when in the first imaging mode, the disconnection control signal Disconnect to be supplied to each disconnection switch SW1 _(n) through the disconnection wiring L_(D1) from the controlling section 40B becomes high level, and each disconnection switch SW1 _(n) closes. Moreover, the discharge control signal Discharge to be supplied to each discharge switch SW2 _(n) through the discharge wiring L_(D2) from the controlling section 40B becomes low level, and each discharge switch SW2 _(n) opens. In this state, each pixel unit P_(m,n) in the range from the first row to the M-th row is connected via the readout wiring L_(O,n) with the signal readout section 20. Then, the same operation as in the case of the first embodiment is performed, whereby a voltage value according to the amount of charges generated in the photodiode PD of each of the M×N pixel units P_(1,1) to P_(M,N) in the photodetecting section 10B is output from the signal readout section 20.

On the other hand, in the solid-state image pickup apparatus 1B according to the second embodiment, when in the second imaging mode, the disconnection control signal Disconnect to be supplied to each disconnection switch SW1 _(n) through the disconnection wiring L_(D1) from the controlling section 40B becomes low level, and each disconnection switch SW1 _(n) opens. Moreover, the discharge control signal Discharge to be supplied to each discharge switch SW2 _(n) through the discharge wiring L_(D2) from the controlling section 40B becomes high level, and each discharge switch SW2 _(n) closes. In this state, each pixel unit P_(m,n) in the range from the first row to the M₁-th row is connected via the readout wiring L_(O,n) with the signal readout section 20, but each pixel unit P_(m,n) in the range from the (M₁+1)-th row to the M-th row is disconnected from the signal readout section 20 and grounded.

Moreover, when in the second imaging mode, in terms of the range from the first row to the M₁-th row, the same operation as in the case of the first embodiment is performed, whereby a voltage value according to the amount of charges generated in the photodiode PD of each pixel unit P_(m,n) is output from the signal readout section 20. On the other hand, in terms of the range from the (M₁+1)-th row to the M-th row, the row selection control signals Vsel(M₁+1) to Vsel(M) become high level, and accordingly, the cathode terminal of the photodiode PD of each pixel unit P_(m,n) is grounded via the readout switch SW₁ and the discharge switch SW2 _(n), and thus the junction capacitance section of the photodiode PD of each pixel unit P_(m,n) is discharged. That is, in this case, each discharge switch SW2 _(n) acts as discharging means for discharging the junction capacitance section of the photodiode PD in each pixel unit P_(m,n) of the range from the (M₁+1)-th row to the M-th row when in the second imaging mode.

When in the second imaging mode, in terms of the range from the (M₁+1)-th row to the M-th row, the row selection control signals Vsel(M₁+1) to Vsel(M) may sequentially become high level, but a plurality of row selection control signals of the row selection control signals Vsel(M₁+1) to Vsel(M) may simultaneously become high level, and all of the row selection control signals Vsel(M₁+1) to Vsel(M) may simultaneously become high level. Thus, in terms of the range from the (M₁+1)-th row to the M-th row, as a result of a plurality or all of the row selection control signals simultaneously becoming high level, the junction capacitance section of the photodiode PD in each pixel unit P_(m,n) can be discharged in a shorter time.

Moreover, when in the second imaging mode, the period for which a voltage value according to the amount of charges generated in the photodiode PD of each pixel unit P_(m,n) is output from the signal readout section 20 in terms of the range from the first row to the M₁-th row, and the period for which the junction capacitance section of the photodiode PD in each pixel unit P_(m,n) is discharged in terms of the range from the (M₁+1)-th row to the M-th row may be partially overlapped with each other. In such a case, a higher-speed operation is possible.

Moreover, as a result of the disconnection wiring L_(D1) being opened when in the second imaging mode, the n-th column readout wiring L_(O,n) to be connected to the signal readout section 20 is shortened, and thus noise can be reduced.

Next, description will be given of an embodiment of an X-ray inspection system including the solid-state image pickup apparatus according to the above embodiment. FIG. 8 is a configuration diagram of the X-ray inspection system 100 according to the present embodiment. The X-ray inspection system 100 according to the present embodiment includes the solid-state image pickup apparatus and an X-ray generator, and images X-rays output from the X-ray generator and transmitted through an inspection object by the solid-state image pickup apparatus to inspect the inspection object.

In the X-ray inspection system 100 shown in this figure, the X-ray generator 106 generates X-rays toward a subject (inspection object). The radiation field of X-rays generated from the X-ray generator 106 is controlled by a primary slit plate 106 b. The X-ray generator 106 has an X-ray tube built therein, and by adjusting conditions of the X-ray tube, such as a tube voltage, a tube current, and energization time, the X-ray dose to the subject is controlled. An X-ray image sensor 107 has a built-in CMOS solid-state image pickup apparatus having a plurality of pixel units arrayed two-dimensionally, and detects an X-ray image transmitted through the subject. In front of the X-ray image sensor 107, a secondary slit plate 107 a that limits an X-ray incident region is provided.

A swing arm 104 holds the X-ray generator 106 and the X-ray image sensor 107 so as to be opposed, and swings these around the subject in panoramic tomography. Moreover, in the case of linear tomography, a sliding mechanism 113 for linearly displacing the X-ray image sensor 107 with respect to the subject is provided. The swing arm 104 is driven by an arm motor 110 that forms a rotary table, and a rotation angle thereof is detected by an angle sensor 112. Moreover, the arm motor 110 is mounted on a movable portion of an XY table 114, and the center of rotation is arbitrarily adjusted in a horizontal plane.

Image signals output from the X-ray image sensor 107 are converted to, for example, 10-bit (=1024 level) digital data by an A/D converter 120, and once taken in a CPU (central processing unit) 121, and thereafter stored in a frame memory 122. From the image data stored in the frame memory 122, a tomographic image along any tomographic plane is reproduced by a predetermined arithmetic processing. The reproduced tomographic image is output to a video memory 124, and converted to analog signals by a D/A converter 125, and then displayed by an image display section 126 such as a CRT (cathode ray tube), and provided for various diagnoses.

The CPU 121 is connected with a work memory 123 required for signal processing, and further connected with an operation panel 119 having a panel switch, an X-ray irradiation switch, etc. Moreover, the CPU 121 is connected to a motor drive circuit 111 that drives the arm motor 110, slit control circuits 115, 116 that control the opening range of the primary slit plate 106 b and the secondary slit plate 107 a, an X-ray control circuit 118 that controls the X-ray generator 106, respectively, and further outputs a clock signal to drive the X-ray image sensor 107.

The X-ray control circuit 118 is capable of feedback-controlling the X-ray dose to the subject based on signals imaged by the X-ray image sensor 107.

In the X-ray inspection system 100 configured as above, the solid-state image pickup apparatus 1A or 1B according to the present embodiment is used as the X-ray image sensor 107.

The X-ray generator 106 can, as a result of the opening range of the slit plate 16 b being controlled, output X-rays at a predetermined divergence angle when in a first output mode, and output X-rays at a narrower divergence angle than the predetermined divergence angle when in a second output mode. When the X-ray generator 106 outputs X-rays in the first output mode, the X-ray image sensor 107 being a solid-state image pickup apparatus operates in the first imaging mode. On the other hand, when the X-ray generator 106 outputs X-rays in the second output mode, the X-ray image sensor 107 being a solid-state image pickup apparatus operates in the second imaging mode.

Here, for example, the first output mode and the first imaging mode correspond to the CT mode described in Patent Document 1, and the second output mode and the second imaging mode correspond to the panoramic mode or cephalographic mode described in Patent Document 1. The solid-state image pickup apparatus 1A, 1B is disposed so that the longitudinal direction of an imaging region (the first row to the M₁-th row) in the photodetecting section 10A, 10B when in the second imaging mode is vertical to a swing plane.

The X-ray inspection system 100 according to the present embodiment includes the solid-state image pickup apparatus 1A or 1B according to the present embodiment, and can thus favorably operate in each imaging mode.

In addition, assuming that the X-ray inspection system 100 including the solid-state image pickup apparatus 1A, 1B is used for a dental application, it is preferable that the number of rows M is larger than the number of columns N in the photodetecting section 10A, 10B of the solid-state image pickup apparatus 1A, 1B. This is attributed to the following reasons. That is, in the first imaging mode corresponding to the CT mode, a size of a light receiving range to be used for imaging in the photodetecting section 10A, 10B of, for example, 8 cm or more×12 cm or more is required. Moreover, in the second imaging mode corresponding to the panoramic mode, a size of a specific range to be used for imaging in the photodetecting section 10A, 10B of, for example, 15 cm or more×7 mm or more is required. In consideration of satisfying the requirements regarding the size as in the above and most efficiently preparing a single integrated solid-state image pickup apparatus 1A, 1B from a circular silicon wafer, the photodetecting section 10A, 10B cannot help but have a rectangular shape long in one direction. Therefore, on the assumption that the photodetecting section 10A, 10B cannot help but have a rectangular shape, the number of columns N is set larger than the number of rows M to reduce the number M of selection control signals to be output from the controlling section 40A, 40B. Moreover, it is preferable to separate the N holding circuits H₁ to H_(N) in the signal readout section 20 into a plurality of sets, provide A/D converting sections individually for the sets, and make these A/D converting sections operate in parallel. This allows realizing a high-speed readout of pixel data.

For example, as shown in FIG. 9, the N integrating circuits S₁ to S_(N) and the N holding circuits H₁ to H_(N) are separated into four sets, where integrating circuits S₁ to S_(i) and holding circuits H₁ to H_(i) are provided as the first set, integrating circuits S_(i+1) to S_(j) and holding circuits H_(i+1) to H_(j) are provided as the second set, integrating circuits S_(j+1) to S_(k) and holding circuits H_(j+1) to H_(k) are provided as the third set, and integrating circuits S_(k+1) to S_(N) and holding circuits H_(k+1) to H_(N) are provided as the fourth set. Here, “1<i<j<k<N.” Voltage values sequentially output from the first set of respective holding circuits H₁ to H_(i) are converted to digital values by an A/D converting section 31, voltage values sequentially output from the second set of respective holding circuits H_(i+1) to H_(j) are converted to digital values by an A/D converting section 32, voltage values sequentially output from the third set of respective holding circuits H_(j+1) to H_(k) are converted to digital values by an A/D converting section 33, and voltage values sequentially output from the fourth set of respective holding circuits H_(k+1) to H_(N) are converted to digital values by an A/D converting section 34. Moreover, A/D converting in the respective four A/D converting sections 31 to 34 are performed in parallel. This allows realizing a high-speed readout of pixel data.

Moreover, in consideration of, for example, binning readout of 2 rows and 2 columns, it is also preferable to provide holding circuits corresponding to odd-numbered columns out of the N holding circuits H₁ to H_(N) as the first set, and holding circuits corresponding to even-numbered columns, as the second set, provide A/D converting sections individually for these first and second sets, respectively, and make these two A/D converting sections operate in parallel. In this case, voltage values are simultaneously output from the holding circuit corresponding to an odd-numbered column and a holding circuit corresponding to an even-numbered column neighboring the odd-numbered column, and these two voltage values are simultaneously A/D converted into digital values. Then, in the case of binning, these two digital values are added. This also allows realizing a high-speed readout of pixel data.

INDUSTRIAL APPLICABILITY

The present invention can be applied to a solid-state image pickup apparatus and an X-ray inspection system.

REFERENCE SIGNS LIST

1A, 1B Solid-state image pickup apparatus

-   10A, 10B Photodetecting section -   20 Signal readout section -   30 A/D converting section -   40A, 40B Controlling section -   P_(1,1) to P_(M,N) Pixel unit -   PD Photodiode -   SW₁ Readout switch -   SW1 ₁ to SW1 _(N) Disconnection switch -   SW2 ₁ to SW2 _(N) Discharge switch -   S₁ to S_(N) Integrating circuit -   C₂₁, C₂₂ Integrating capacitor -   SW₂₁ Discharge switch -   A₂ Amplifier -   H₁ to H_(N) Holding circuit -   C₃ Holding capacitor -   SW₃₁ Input switch -   SW₃₂ Output switch -   L_(V,m) m-th row selecting wiring -   L_(H,n) n-th column selecting wiring -   L_(O,n) n-th column readout wiring -   L_(R) Reset wiring -   L_(G) Gain setting wiring -   L_(H) Holding wiring -   L_(out) Voltage outputting wiring 

The invention claimed is:
 1. An X-ray inspection system used for a dental application, comprising: a solid-state image pickup apparatus; and an X-ray generator, wherein the X-ray output from the X-ray generator transmits through an inspection object to form an X-ray image, and the X-ray image is picked up by the solid-state image pickup apparatus to inspect the inspection object, where M and N are each an integer not less than 2, M₁ is an integer less than M, N₁ is an integer less than N, m is an integer not less than 1 and not more than M, and n is an integer not less than 1 and not more than N, wherein the solid-state image pickup apparatus comprises: a photodetecting section where M×N pixel units P_(l,1) to P_(M,N), each including a photodiode that generates a charge of an amount according to an incident light intensity and a readout switch connected with the photodiode, are two-dimensionally arrayed in M rows and N columns, a readout wiring L_(O,n) connected with a readout switch of each of the M pixel units P_(1,n) to P_(M,n) of an n-th column in the photodetecting section, for reading out a signal caused by charges generated in the photodiode of any pixel unit of the M pixel units P_(1,n) to P_(M,n) via the readout switch of the pixel unit; a signal readout section including N holding circuits H₁ to H_(N), each of the holding circuits being connected with each of the readout wirings L_(O,1) to L_(O,N), for holding a voltage value caused by the signal from the readout wiring L_(O,n), and sequentially outputting the held voltage values; and a controlling section that controls an opening and closing operation of the readout switch of each of the M×N pixel units P_(1,1) to P_(M,N) in the photodetecting section and controls an outputting operation of a voltage value in the signal readout section to make a voltage value according to an amount of charge generated in the photodiode of each of the M×N pixel units P_(1,1) to P_(M,N) in the photodetecting section be output from the signal readout section, wherein the controlling section when in a first imaging mode, makes a voltage value according to an amount of charge generated in the photodiode of each of the M×N pixel units P_(1,1) to P_(M,N) in the photodetecting section be output from the signal readout section, and when in a second imaging mode, makes a voltage value according to an amount of charge generated in the photodiode of each pixel unit P_(m,n) included in a specific range of consecutive M₁ rows in the photodetecting section be output from the signal readout section, wherein the solid-state image pickup apparatus and the X-ray generator are rotatable around the inspection object while facing each other, or the image pickup apparatus is linearly movable with respect to the inspection object, wherein a direction of the rotation movement or a direction of the linear movement is perpendicular to a longitudinal direction of the specific range in the photodetecting section in the second imaging mode.
 2. The X-ray inspection system according to claim 1, wherein the controlling section, when in the second imaging mode, has as the specific range, a range of M₁ rows counted in order from the row closest to the signal readout section out of the M rows in the photodetecting section, and makes a voltage value according to the amount of charge generated in the photodiode of each pixel unit P_(m,n) in the specific range be output from the signal readout section.
 3. The X-ray inspection system according to claim 2, further comprising, between the specific range in the photodetecting section and another range excluding the specific range, a disconnection switch provided on each readout wiring L_(O,n), wherein the controlling section closes the disconnection switch when in the first imaging mode, and opens the disconnection switch when in the second imaging mode.
 4. The X-ray inspection system according to claim 1, including discharging means that discharges a junction capacitance section of the photodiode in each pixel unit P_(m,n) of another range excluding the specific range in the photodetecting section when in the second imaging mode.
 5. The X-ray inspection system according to claim 1, further comprising a scintillator section that is provided so as to cover the M×N pixel units P_(1,1) to P_(M,N) in the photodetecting section.
 6. An X-ray inspection system used for a dental application, comprising a solid-state image pickup apparatus; and an X-ray generator, wherein the X-ray output from the X-ray generator transmits through an inspection object to form an X-ray image, and the X-ray image is picked up by the solid-state image pickup apparatus to inspect the inspection object, where M and N are each an integer not less than 2, M₁ is an integer less than M, N₁ is an integer less than N, m is an integer not less than 1 and not more than M, and n is an integer not less than 1 and not more than N, wherein the solid-state image pickup apparatus comprises: a photodetecting section where M×N pixel units P_(1,1) to P_(M,N) each including a photodiode that generates a charge of an amount according to an incident light intensity and a readout switch connected with the photodiode are two-dimensionally arrayed in M rows and N columns; a readout wiring L_(O,n), connected with a readout switch of each of the M pixel units P_(1,n), to P_(M,n) of an n-th column in the photodetecting secion, for reading out a signal caused by charges generated in the photodiode of any pixel unit of the M pixel units P_(1,n) to P_(M,n) via the readout switch of the pixel unit; a signal readout section including N holding circuits H₁ to H_(N), each of the holding circuits being connected with each of the readout wirings L_(0,1), to L_(0,N), for holding a voltage value caused by the signal from the readout wiring L_(O) _(n) , and sequentially outputting the held voltage values; and a controlling section that controls an opening and closing operation of the readout switch of each of the M×N pixel units P_(1,1) to P_(M,N) in the photodetecting section and controls an outputting operation of a voltage value in the signal readout section to make a voltage value according to an amount of charge generated in the photodiode of each of the M×N pixel units P_(1,1) to P_(M,N) in the photodetecting section be output from the signal readout section, wherein the controlling section when in a first imaging mode, makes a voltage value according to an amount of charge generated in the photodiode of the photodetecting section be output from the signal readout section, and when in a second imaging mode, makes a voltage value according to an amount of charge generated in the photodiode of each pixel unit Pm,i included in a specific range of consecutive M₁ rows in the photodetecting section be output from the signal readout section, wherein the solid-state image pickup apparatus and the X-ray generator are retatable around the inspection object while facing each other, or the image pickup apparatus is linearly movable with respect to the inspection object, wherein a direction of the rotation movement ofr a direction of the linear movement is perpendicular to a longitudinal direction of the specific range in the photodetecting section in the second imaging mode.
 7. The X-ray inspection system according to claim 6, wherein the controlling section, when in the second imaging mode, has as the specific range, a range of M₁ rows counted in order from the row closest to the signal readout section out of the M rows in the photodetecting section, and makes a voltage value according to the amount of charge generated in the photodiode of each pixel unit P_(m,n) in the specific range be output from the signal readout section.
 8. The X-ray inspection system according to claim 7, further comprising, between the specific range in the photodetecting section and another range excluding the specific range, a disconnection switch provided on each readout wiring L_(O,n), wherein the controlling section closes the disconnection switch when in the first imaging mode, and opens the disconnection switch when in the second imaging mode.
 9. The X-ray inspection system according to claim 6, including discharging means that discharges a junction capacitance section of the photodiode in each pixel unit P_(m,n) of another range excluding the specific range in the photodetecting section when in the second imaging mode.
 10. The X-ray inspection system according to claim 6, further comprising a scintillator section that is provided so as to cover the M×N pixel units P_(1,1) to P_(M,N) in the photodetecting section. 